Abstract Dr. Al-Balas is a clinical investigator with a research focus on hemodialysis vascular access. This award will provide Dr. Al-Balas the support necessary to become skilled in patient-oriented clinical research on individuals with hemodialysis vascular access dysfunction. To achieve these goals Dr. Al-Balas has assembled a team of mentors with a wealth of research experience and a track-record in mentoring junior investigators. When this is combined with the exceptional resources, institutional support, and the proposed career development activities, Dr. Al-Balas will be well positioned to achieve his long-term goal. Surgically created arteriovenous fistulas (AVFs), the current gold standard technique for establishing a channel between an artery and vein for hemodialysis (HD), are associated with several problems, including a high rate of non-maturation, a frequent requirement for a second procedure prior to successful use (assisted maturation), and frequent interventions to maintain AVF patency after maturation. An endovascular AVF (endo- AVF) creation is a novel and promising non-surgical approach that became available in the U.S. in 2019. Uncontrolled pilot studies with endo-AVFs suggest that their clinical outcomes are superior to those obtained with the standard surgical AVF creation, but head-to-head comparisons are lacking. The potential advantages of endo-AVFs can be definitively addressed only by a randomized clinical trial (RCT) comparing endo-AVFs to surgical AVFs in terms of physiological maturation, clinical maturation, overall survival, frequency of procedures and cost. The goal of our study is to establish a solid foundation for such an RCT. First, we will compare the two UAB cohorts in term of short term AVF outcomes (physiological maturation at 6 weeks and clinical maturation at 6 months) and long-term vascular access outcomes (secondary patency and frequency of interventions after maturation), and costs of access management. This analysis will also provide critical information required to perform the necessary power calculations for an RCT. Second, we will pilot an RCT of endo-AVFs vs surgical AVFs, to determine the feasibility of patient recruitment, randomization, and retention at UAB. Finally, we will utilize the USRDS database to compare the outcomes of endo-AVFs and surgical AVFs in a national cohort, and to calculate the overall cost of access management with each technique. My ultimate goal is to become an independent patient-oriented clinical investigator. A K23 mentored career development award will provide me protected time critical to complete the research project outlined in this proposal and gain more expertise in research methods through formal training, including completing a Masters in Science in Public Health. The current proposal will provide critical data that will form the foundation for a future independent research grant. My long-term objective is to develop optimal vascular access strategies to reduce vascular access complications and their costs in hemodialysis patients.